Effect of Simulated Gastric Acid on the Interface Between Zirconia and Resin Cement

PURPOSE

To evaluate the effect of simulated gastric acid solution (SGAS) and resin cement composition on the shear bond strength (SBS) of zirconia-based materials with different levels of translucency to composite resin.

MATERIALS AND METHODS

A total of 40 medium-opacity (MO; 3Y-TZP) and 40 medium-translucency (MT; 4Y-PSZ) zirconia slabs were distributed into four groups according to the composition of the resin luting system (MDP free or with MDP [primer + Panavia V5]) and storage method (distilled water or SGAS [5% hydrochloric acid]). Composite resin cylinders were cemented on the zirconia surface and stored for 91 hours. SBS, failure mode, and surface characterization analyses via scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS) were performed. SBS data were analyzed using three-way ANOVA and Tukey tests, and failure mode was assessed using one-way ANOVA (P < .05).

RESULTS

Storage media (P = .180), resin cement (P = .110), zirconia (P = .404), and their interactions did not affect SBS values. Bond strength ranged from 21.41 to 26.11 MPa. SEM images showed that SGAS modified the surface topography of zirconia and resin cement. The presence of chlorine and silicon (wt%) were higher after SGAS storage than after water storage in both cements used, while barium was higher only for the MDP cement. There was a prevalence of mixed failures for most of the groups.

CONCLUSIONS

The SBS between both types of zirconia and resin cement was not affected by SGAS, although changes in zirconia topography were observed after SGAS exposure. The presence of MDP in the cement layer had no effect on the SBS challenged by SGAS.

Sodium citrate buffer improves pazopanib solubility and absorption in gastric acid-suppressed rat model

Pazopanib exhibits pH-dependent solubility and its absorption depends primarily on the stomach pH. Significant decrease of pazopanib absorption by coadministration with proton pump inhibitors in clinical situation need to be overcome. Thus, the purpose of this study is firstly to investigate the effect of acidic beverages and sodium citrate buffer on the solubility of pazopanib and secondly to examine the effect of sodium citrate buffer on pazopanib absorption in a rat model with esomeprazole-mediated gastric acid suppression. Pazopanib solubility decreased with increasing pH of sodium citrate buffer in vitro. Interestingly, its solubility in some acidic beverages was significantly lower than that in sodium citrate buffer of the same pH. The AUC0-24h of pazopanib administered in tap water to rats treated with esomeprazole (ESP rats) was 66 % lower than that in the control rats treated with saline. However, AUC0-24h was 4.8 times higher in ESP rats that received pazopanib with sodium citrate buffer (pH 2.3) compared to ESP rats that received pazopanib with tap water. Our results indicate that the drug-drug interactions between pazopanib and proton pump inhibitors can be overcome, at least in part, by suspending pazopanib in sodium citrate buffer.

Gastric Acid Suppression Therapy and Its Association with Peritoneal Dialysis-Associated Peritonitis in the Peritoneal Dialysis Outcomes and Practice Patterns Study (PDOPPS)

Key Points

In a large multinational cohort of PD patients, any GAS use was not associated with an increased risk of all-organism peritonitis. For peritonitis, risks were particularly high among certain classes of organisms particularly for Gram-negative, enteric, and streptococcal peritonitis episodes. The association with enteric peritonitis appeared to be stronger among H2RA users.

Background

Peritonitis is a major peritoneal dialysis–related complication. We determined whether gastric acid suppression (GAS) (proton pump inhibitor [PPI] or histamine-2 receptor antagonists [H2RAs]) use was associated with all-cause and organism-specific peritonitis in peritoneal dialysis patients.

Methods

In the Peritoneal Dialysis Outcomes and Practice Patterns Study (595 facilities, eight countries, years 2014–2022), associations between GAS use and time to first episode of all-cause peritonitis were examined using Cox proportional hazards models. The primary exposure of interest was GAS and secondarily PPI or H2RA use. Secondary outcomes were organism-specific peritonitis, peritonitis cure rates, and death.

Results

Among patients (N =23,797) at study baseline, 6020 (25.3%) used PPIs, and 1382 (5.8%) used H2RAs. Overall risks of GAS use and peritonitis risk (adjusted hazard ratio [AHR]=1.05, 95% confidence interval [CI], 0.98 to 1.13]) and use of PPI (AHR 1.06 [95% CI, 0.99 to 1.14]) or H2RA (AHR 1.02 [95% CI, 0.88 to 1.18]) did not reach statistical significance. In organism-specific analyses, GAS users displayed higher peritonitis risks for Gram-negative (AHR 1.29, 95% CI, 1.05 to 1.57), Gram-positive (AHR 1.15, 95% CI, 1.01 to 1.31), culture-negative (AHR 1.20, 95% CI, 1.01 to 1.42), enteric (AHR 1.23, 95% CI, 1.03 to 1.48), and particularly Streptococcal (AHR 1.47, 95% CI, 1.15 to 1.89) peritonitis episodes. GAS was also associated with higher overall mortality (AHR 1.13 [95% CI, 1.05 to 1.22]).

Conclusion

The association between GAS use and peritonitis risk was weaker (hazard ratio [HR] 1.05 [0.98 to 1.13]) than for streptococcal (HR 1.57 [1.15 to 1.89]) and Gram-negative (HR 1.29 [1.05 to 1.57]) peritonitis. A better understanding of mechanisms surrounding the differential effects of GAS subtype on peritonitis risks is needed. Clinicians should be cautious when prescribing GAS. The impact of GAS deprescribing on peritonitis risk requires further evaluation.

Gastric acid-responsive deformable sodium alginate/Bletilla striata polysaccharide in situ gel for the protection and treatment of alcohol-induced peptic ulcers

First-line drugs for peptic ulcer (PU) treatment are typically limited by poor targeting and adverse effects associated with long-term use. Despite recent advancements in novel therapeutic approaches for PU, the development of sustained-release delivery systems tailored to specific pathological characteristics remains challenging. Persistent inflammation, particularly gastric inflammatory microenvironment imbalance, characterizes the PU. In this study, we prepared an in situ gel composed of sodium alginate, deacetylated gellan gum, calcium citrate, and Bletilla striata polysaccharide (BSP) to achieve sustained release of BSP. The BSP in situ gel demonstrated favorable fluidity in vitro and completed self-assembly in vivo in response to the acidic milieu at a pH of 1.5. Furthermore, the shear, extrusion, and deformation properties increased by 26.4 %, 103.7 %, and 46.3 %, respectively, with long-term gastric retention (4 h) and mucosal adaptation. Animal experiments confirmed that the BSP in situ gel could attenuate necrotic injury and inflammatory cell infiltration, maintain mucosal barrier integrity, regulate cytokine imbalance and inflammation-associated hyperapoptosis, thus effectively alleviate the inflammatory microenvironmental imbalance in PU without significant side effects. Overall, our findings demonstrated that the BSP in situ gel is a promising therapeutic strategy for PU and opens avenues for developing self-assembled formulations targeting the pathological features of PUs.

Neuroendocrine mechanism of gastric acid secretion: Historical perspectives and recent developments in physiology and pharmacology

The physiology of gastric acid secretion is one of the earliest subjects in medical literature and has been continuously studied since 1833. Starting with the notion that neural stimulation alone drives acid secretion, progress in understanding the physiology and pathophysiology of this process has led to the development of therapeutic strategies for patients with acid-related diseases. For instance, understanding the physiology of parietal cells led to the developments of histamine 2 receptor blockers, proton pump inhibitors (PPIs), and recently, potassium-competitive acid blockers. Furthermore, understanding the physiology and pathophysiology of gastrin has led to the development of gastrin/CCK2 receptor (CCK2 R) antagonists. The need for refinement of existing drugs in patients have led to second and third generation drugs with better efficacy at blocking acid secretion. Further understanding of the mechanism of acid secretion by gene targeting in mice has enabled us to dissect the unique role for each regulator to leverage and justify the development of new targeted therapeutics for acid-related disorders. Further research on the mechanism of stimulation of gastric acid secretion and the physiological significances of gastric acidity in gut microbiome is needed in the future.

Gastric acid challenge of lithium disilicate-reinforced glass-ceramics and zirconia-reinforced lithium silicate glass-ceramic after polishing and glazing-impact on surface properties

OBJECTIVES

To investigate the impact of simulated gastric acid on the surface properties of lithium disilicate-reinforced glass-ceramics and zirconia-reinforced lithium silicate glass-ceramic after certain polishing and glazing procedures.

MATERIALS AND METHODS

Four different types of square-shaped specimens (10 × 10 × 2 mm3, n = 13) were manufactured: lithium disilicate-reinforced glass-ceramic milled and polished (LDS-P); milled, polished, and glazed (LDS-PG); milled, glazed, and no polishing (LDS-G); and milled and polished zirconia-reinforced lithium silicate glass-ceramic (ZR-LS). Specimens were immersed in hydrochloride acid (HCl 0.06 M, pH 1.2) to simulate gastric acid irritation and stored in the acid for 96 h in 37 °C. Specimen weight, surface gloss, Vickers surface microhardness and surface roughness (Ra, Rq, with optical profilometer), and surface roughness on nanometer level (Sq, Sal, Sq/Sal, Sdr, Sds with atomic force microscope) were measured before and after the acid immersion.

RESULTS

ZR-LS specimens lost significantly more weight after acid immersion (p = 0.001), also surface microhardness of ZR-LS was significantly reduced (p = 0.001). LDS-G and LDS-PG showed significantly lower surface roughness (Sa, Sq) values compared to LDS-P before (p ≤ 0.99) and after (p ≤ 0.99) acid immersion and ZR-LS after acid immersion (p ≤ 0.99).

CONCLUSIONS

Gastric acid challenge affects the surface properties of lithium disilicate-reinforced glass-ceramic and zirconia-reinforced lithium silicate glass-ceramic. Glazing layer provides lower surface roughness, and the glazed surface tends to smoothen after the gastric acid challenge.

CLINICAL RELEVANCE

Surface finish of lithium disilicate-reinforced glass-ceramic and zirconia-reinforced lithium silicate glass-ceramic has a clear impact on material's surface properties. Gastric acidic challenge changes surface properties but glazing seems to function as a protective barrier. Nevertheless, also glazing tends to smoothen after heavy gastric acid challenge. Glazing can be highly recommended to all glass-ceramic restorations but especially in patients with gastroesophageal reflux disease (GERD) and eating disorders like bulimia nervosa.

Effect of simulated gastric acid on aesthetical restorative CAD-CAM materials' microhardness and flexural strength

Background

Gastric acid, which is among erosive substances, gradually rises to the mouth in individuals with reflux and bulimia nervosa disorders, and this causes various effects on dental restorations.

Aim

The objective of this study is in vitro investigation of gastric acid's effect on flexural strength and hardness on aesthetic restorative computer-aided design and computer-aided manufacturing (CAD-CAM) materials.

Materials and Methods

For this study, four materials have been used, namely Enamic (Vita), Superfect Zir (Aidite) Zirconia, IPS e.max CAD (Ivoclar Vivadent), and Mark II (Vita). From these four different materials, 24 samples with 14 × 4 × 1 dimensions in rectangular prism form are used, which makes a total of 96 samples. One group was separated as the control group, while the rest was allowed to wait at 37°C, 5 ml gastric acid for 96 hours. Hardness value and flexural strengths were measured as pre-exposure and post-exposure to gastric acid.

Results

There is a statistically significant difference between the groups in terms of the amount of decrease in the mean hardness after exposure to gastric acid compared to pre-exposure values (p: 0,000; P < 0,05). There was no statistically significant difference between the groups in terms of the amount of decrease in the post-exposure average flexural strength compared to the pre-exposure value (p: 0.063; P > 0.05). There is a statistically significant difference between the groups in terms of the average flexural strength after exposure to the acid.

Conclusions

According to the data obtained, it was concluded that exposure to gastric acid affects the hardness and flexural strength properties of dental restorative ceramic materials.

The effects of gastric acid on pediatric restorative materials: SEM analysis

In this study, we aimed to demonstrate changes in the surface roughness and microhardness of three different restorative materials routinely used in pediatric dentistry (composite, compomer and resin-modified glass ionomer cement (RMCIS)) in response to continuous daily exposure to gastric acid. Twelve samples of each of type of restorative material were prepared. Eleven of the specimens were included in the gastric acid cycle. The microhardness and surface roughness of ten samples were measured before and after the cycle. Another sample included in the cycle was compared with the sample not included in the cycle by scanning electron microscopy (SEM). There was a significant difference between the groups in terms of roughness scores following gastric acid cycle (p = 0.039). RMCIS material possessed the highest roughness value. A significant difference was identified in terms of microhardness levels before and after the gastric acid cycle (p = 0.001). The most significant change was observed in the compomer material. SEM analysis, performed after the gastric acid cycle, revealed that most cracks were identified in RMCIS material; this was followed by compomer and composite materials, respectively. Our analysis indicates that the restorative materials used frequently in pediatric dental procedures, show increased surface roughness and reduced microhardness when exposed to gastric acid.

Twenty-four-hour pH metry alone is inferior to additional impedance monitoring in the diagnosis of gastroesophageal reflux disease, particularly in presence of reduced gastric acid secretion

BACKGROUND

Current gold standard for the diagnosis of gastroesophageal reflux disease (GERD) is 24-hour pH metry though it fails to detect non-acidic reflux. The sensitivity of 24-hour pH metry alone (both catheter-based and Bravo capsule) is questionable, especially if gastric acid secretion is low due to reduced parietal cell mass, Helicobacter pylori-induced gastric atrophy and antisecretory therapy. Accordingly, we analyzed the diagnostic ability of 24-hour pH metry as compared to impedance monitoring in relation to the gastric pH without antisecretory therapy.

METHODS

A retrospective analysis of prospectively collected data from 150 patients with suspected GERD undergoing a 24-hour pH impedance study was done.

RESULTS

Among 150 patients with symptoms suggestive of GERD, 106 (70.6%) had confirmed GERD diagnosed either by 24-hour pH metry alone (10 [9.4%]), impedance monitoring alone (49 [46.2%]) or both (47 [44.3%]). Abnormal reflux of acidic and non-acidic gastric contents was detected by 24-hour pH metry and 24-hour impedance monitoring in 57/106 (53.7%) and 96/106 (90.5%) of patients, respectively (p < .00001). Patients with GERD diagnosed by 24-hour impedance monitoring had a higher mean gastric pH (2.9 [median 1.3, IQR 5.3]) than those diagnosed by 24-hour pH metry (2.1 [median 1.4, IQR 2.6]) or both (1.6 [median 1.2, IQR 2.1]) (p = 0.001).

CONCLUSION

Twenty-four-hour impedance monitoring detects GERD more often than 24-hour pH metry. Patients with higher mean gastric pH leading to non-acidic reflux were more often diagnosed by 24-hour impedance monitoring than 24-hour pH metry. Thus, 24-hour pH metry alone is inferior to additional impedance monitoring in the diagnosis of GERD, particularly in presence of reduced gastric acid secretion.

Simulated Gastric Acid Promotes the Horizontal Transfer of Multidrug Resistance Genes across Bacteria in the Gastrointestinal Tract at Elevated pH Levels

The assessment of factors that can promote the transmission of antibiotic resistance genes (ARGs) across bacteria in the gastrointestinal tract is in great demand to understand the occurrence of infections related to antibiotic-resistant bacteria (ARB) in humans. However, whether acid-resistant enteric bacteria can promote ARG transmission in gastric fluid under high-pH conditions remains unknown. This study assessed the effects of simulated gastric fluid (SGF) at different pH levels on the RP4 plasmid-mediated conjugative transfer of ARGs. Moreover, transcriptomic analysis, measurement of reactive oxygen species (ROS) levels, assessment of cell membrane permeability, and real-time quantitative assessment of the expression of key genes were performed to identify the underlying mechanisms. The frequency of conjugative transfer was the highest in SGF at pH 4.5. Antidepressant consumption and certain dietary factors further negatively impacted this situation, with 5.66-fold and 4.26-fold increases in the conjugative transfer frequency being noted upon the addition of sertraline and 10% glucose, respectively, compared with that in the control group without any additives. The induction of ROS generation, the activation of cellular antioxidant systems, increases in cell membrane permeability, and the promotion of adhesive pilus formation were factors potentially contributing to the increased transfer frequency. These findings indicate that conjugative transfer could be enhanced under certain circumstances in SGF at elevated pH levels, thereby facilitating ARG transmission in the gastrointestinal tract. IMPORTANCE The low pH of gastric acid kills unwanted microorganisms, in turn affecting their inhabitation in the intestine. Hence, studies on the factors that influence antibiotic resistance gene (ARG) propagation in the gastrointestinal tract and on the underlying mechanisms are limited. In this study, we constructed a conjugative transfer model in the presence of simulated gastric fluid (SGF) and found that SGF could promote the dissemination of ARGs under high-pH conditions. Furthermore, antidepressant consumption and certain dietary factors could negatively impact this situation. Transcriptomic analysis and a reactive oxygen species assay revealed the overproduction of reactive oxygen species as a potential mechanism by which SGF could promote conjugative transfer. This finding can help provide a comprehensive understanding of the bloom of antibiotic-resistant bacteria in the body and create awareness regarding the risk of ARG transmission due to certain diseases or an improper diet and the subsequent decrease in gastric acid levels.

Synthetic Lignin-Derived Therapeutic Nano Reagent as Intestinal pH-Sensitive Drug Carriers Capable of Bypassing the Gastric Acid Environment for Colitis Treatment

Oral drug delivery is a common route for management of inflammatory bowel disease (IBD) but suffers from low bioavailability and systemic side effects during passage through the alimentary canal. Here, we present a therapeutic nano reagent of a ferulic acid-derived lignin nanoparticle (FALNP). We showed that FALNP with favorable antioxidant activity can regulate IBD. More importantly, the intestinal pH-responsive degradability of FALNP allows it to withstand the harsh gastric acid environment, bypass physiological barriers, and target the intestine for gastrointestinal delivery. In vivo experiments showed that oral administration of FALNP markedly relieved pathological symptoms in a mouse model of acute colitis by reducing oxidative stress and regulating the gut microbiome. By integrating anti-inflammatory medicine, FALNP also can be used as a bioactive carrier to exert a potent synergistic therapeutic effect. In addition to colitis, FALNP can be readily adaptable for use as a carrier platform for therapy of many other intestinal diseases.

Gastric acid and escape to systemic circulation represent major bottlenecks to host infection by Citrobacter rodentium

The gastrointestinal (GI) environment plays a critical role in shaping enteric infections. Host environmental factors create bottlenecks, restrictive events that reduce the genetic diversity of invading bacterial populations. However, the identity and impact of bottleneck events on bacterial infection are largely unknown. We used Citrobacter rodentium infection of mice, a model of human pathogenic Escherichia coli infections, to examine bacterial population dynamics and quantify bottlenecks to host colonization. Using Sequence Tag-based Analysis of Microbial Populations (STAMP) we characterized the founding population size (Nb') and relatedness of C. rodentium populations at relevant tissue sites during early- and peak-infection. We demonstrate that the GI environment severely restricts the colonizing population, with an average Nb' of only 12-43 lineages (of 2,000+ inoculated) identified regardless of time or biogeographic location. Passage through gastric acid and escape to the systemic circulation were identified as major bottlenecks during C. rodentium colonization. Manipulating such events by increasing gastric pH dramatically increased intestinal Nb'. Importantly, removal of the stomach acid barrier had downstream consequences on host systemic colonization, morbidity, and mortality. These findings highlight the capability of the host GI environment to limit early pathogen colonization, controlling the population of initial founders with consequences for downstream infection outcomes.

The Effect of Gastric Acid on the Surface Properties of Different Universal Composites: A SEM Study

The aim of this study is to compare surface roughness and microhardness changes of three monochromatic (Omnichroma, Vittra Unique, and Charisma Diamond One) and three universal shade (Neo Spectra ST, G-ænial A'CHORD, and Nova Compo C) resin composites after exposure to simulated gastric acid. A total of 144 disc-shaped specimens (24 discs of each composite resin) were prepared using plexiglass molds (R = 5 mm × h = 2 mm) for evaluation from each material. Specimens of each material were divided into two main groups for the evaluation of the microhardness and surface roughness and also two subgroups for 7- and 14-day exposures to simulated gastric acid. Initial microhardness and surface roughness measurements of all samples were measured before immersion (T1) followed by exposing the samples to simulated gastric acid for 7 days (T2) and 14 days (T3), and then, the microhardness and roughness measurements were repeated. Randomly selected specimens of each material for each of the time intervals (T1, T2, and T3) were evaluated with scanning electron microscopy (SEM). One-way ANOVA revealed that the surface roughness and hardness values of all tested composite resin restorative materials show no statistically significant difference for the initial (T1) value (p > 0.05). Regarding the 7^th day (T2) and 14^th day (T3) surface roughness and microhardness value of all composites, there are statistically significant differences between the groups (p < 0.05), while there was no statistically significant difference between the surface hardness reduction percentage between the time intervals (p > 0.05). As a result of this in vitro study, increase in surface roughness and decrease in microhardness of the tested universal composite materials when exposed to simulated gastric acid were statistically significant.

[Clinical practice guideline for appropriate use of gastric acid suppressants in gastrointestinal surgery (2022 edition)]

Gastric acid suppressants, such as proton pump inhibitors, are one of the most widey used drugs worldwide. There is a very high frequency of abuse of gastric acid suppressants, leading huge waste of medical resources. Moreover, numerous studies have showed that acid suppressants were associated with a variety of adverse events, such as fractures and intestinal infections. Increasing guidelines and consensuses have been made to guide the appropriate use of acid suppressants. Gastrointestinal surgery is one of the fields with the largest prescriptions of acid suppressants. Acid suppressants are widely used for preventing anastomotic bleeding after upper gastrointestinal surgery, treating gastrointestinal bleeding and etc. However, most of these prescriptions are off-label uses lacking adequate evidentiary basis. Thus far, there is no guideline specific for appropriate use of acid suppressants in digestive surgeries. Therefore, Chinese Society of Upper Gastrointestinal Surgeons (CSUGS) and Chinese Gastric Cancer Association (CGCA) developed this clinical practice guideline based on the best research evidence and clinical expertise. The aim is to guide the appropriate use of gastric acid suppressants in gastrointestinal surgery, which in turn, increase the benefits of patients.

In Vitro Evaluation of Gastric Acid and Toothbrushing Effect on the Surface State of Different Types of Composite Resins

Background and Objectives: The aim of this in vitro study was to evaluate the effect of gastric acid associated with the effect of toothbrushing on the surface roughness of different types of composite resin used for direct restorations. Materials and Methods: The materials used in this study were two microhybrid (Filtek Z250, Herculite XRV) and two nanohybrid (Filtek Z550, Herculite XRV Ultra) composite resins. Two hundred and forty cylindrical samples with a height of 2 mm and a diameter of 6 mm were divided into four groups (groups A, B, C and D) corresponding to each tested material (n = 60). Each group was divided in two subgroups: subgroup I—the samples were submersed in hydrochloric acid and immediately submitted to toothbrushing; subgroup II—the samples were submitted only to toothbrushing. The simulation of the acid attack was performed by immersing the samples in a 0.01 M hydrochloric acid solution for 90 min. This procedure was followed immediately by toothbrushing simulation with 10,000 cycles. The acid attack and toothbrushing simulation were performed for two times. The surface roughness evaluation was performed with a Proscan 2100 profilometer. Repeated Measures ANOVA and Bonferroni post-hoc tests were used to perform the statistical analysis. Results: Simulation of one year of toothbrushing associated or not to hydrochloric acid exposure increases the surface roughness of microhybrid and nanohybrid composite resins. Six months of toothbrushing associated to six months of hydrochloric acid exposure increase the surface roughness of nanohybrid composite resins. Conclusions: Microhybrid composite resins surface becomes rougher after toothbrush and acid submersion when comparing to nanohybrid composite resins.

The Impact of Simulated Gastric Acid and Toothbrushing on Surface Characteristics of Resin-Modified Glass-Ionomer Cements

Background and Objectives: The aim of this in vitro study was to evaluate the effect of simulated gastric acid associated with toothbrushing on the surface condition of three resin-modified glass-ionomer cements (RMGIC). Materials and Methods: One hundred and sixty samples of each material were obtained and included in three study groups according to the tested material: Group I (Ionolux, VOCO GmbH, Cuxhaven, Germany); Group II (Vitremer, 3 M-ESPE, St. Paul, MN, USA); and Group III (Fuji II LC, GC Corporation, Tokyo, Japan). The samples were submersed in hydrochloric acid 0.01 M (pH 3.8) for 3 h and exposed to a toothbrushing procedure at a frequency of 10,000 cycles with medium and hard bristles immediately or 30 min after the acid attack. Profilometric measurements were performed by using a non-contact profilometer (Dektak XT, Bruker, Billerica, MA, USA) in order to assess the surface roughness. ANOVA and Bonferroni post hoc tests were used for the statistical analysis at a significance level of p < 0.05. Results: Exposure of RMGICs to the erosive effect of hydrochloric acid in association with toothbrushing 30 min after the chemical attack increased the surface roughness of all three RMGICs. Exposure of the three tested materials exclusively to the action of hydrochloric acid did not affect the surface roughness. Conclusions: One year of hydrochloric acid challenge associated with one year of toothbrushing with medium-hardness bristles performed 30 min after the acid attack increase the surface roughness of two of the three types of RMGIC tested (Ionolux and Fuji II LC).

Pepsin and pH of Gastric Juice in Patients With Gastrointestinal Reflux Disease and Subgroups

GOAL

The aim of this study was to investigate the pepsin values and pH results of gastric juice among the subtypes of gastroesophageal reflux disease (GERD) and functional heartburn.

BACKGROUND

The major destructive agents of GERD on the esophageal epithelium are gastric acid and pepsin. No precise information about pepsin concentration in gastric juice exists.

STUDY

Ninety patients with GERD, 39 erosive reflux disease (ERD) Los Angeles (LA) grade A/B, 13 ERD LA grade C/D, 19 nonerosive reflux disease (NERD), 8 esophageal hypersensitivity, 11 functional heartburn, and 24 healthy controls were included in the study. During endoscopy gastric juices from the patients were aspirated and their pH readings immediately recorded. Gastric juice samples were analyzed using Peptest, a lateral flow device containing 2 unique human monoclonal antibodies to detect any pepsin present in the gastric juice sample.

RESULTS

The highest mean gastric pepsin concentration (0.865 mg/mL) and the lowest median gastric pH (1.4) was observed in the LA grade C/D group compared with the lowest mean gastric pepsin concentration (0.576 mg/mL) and the highest median gastric pH (2.5) seen in the NERD group. Comparing pH, the NERD patient group was significantly higher (P=0.0018 to P=0.0233) when compared with all other GERD patient groups.

CONCLUSIONS

The basal gastric pepsin level in the healthy control group was comparable to literature values. There was good correlation and a significant linear relationship between the gastric pepsin level and gastric pH within the patient groups. The severity of the GERD disease is related to the lowest pH and the highest pepsin concentration in gastric juice.

Influence of concomitant gastric acid suppressants use on the survival of patients with non-small cell lung cancer treated with programmed death-1/ligand-1 inhibitors: A meta-analysis

INTRODUCTION

Influence of concomitant use of gastric acid suppressants (GAS) on survival of non-small cell lung cancer (NSCLC) patients receiving programmed death-1/ligand-1 (PD-1/PD-L1) inhibitors has rarely been comprehensively evaluated. A meta-analysis was performed to systematically evaluate the effect of concomitant GAS in NSCLC patients receiving PD-1/PD-L1inhibitors.

METHODS

Relevant observational studies were identified by search of Medline, Embase, and Web of Science databases from inception to May 26, 2022. A random-effect model which incorporates the possible between-study heterogeneity was used to combine the results.

RESULTS

Ten retrospective and one prospective cohort studies including 5892 patients were patients were included. Influence of concomitant proton pump inhibitors (PPIs) was evaluated in ten studies, and influence of GAS, including PPIs or histamine type-2 receptor antagonists were evaluated in one study. Pooled results showed that concomitant use of GAS was associated with worse progression-free survival (PFS, adjusted hazard ratio [HR]: 1.32, 95% confidence interval [CI]: 1.20 to 1.45, P < 0.001; I² = 0%) and overall survival (OS, adjusted HR: 1.36, 95% CI: 1.26 to 1.48, P < 0.001; I² = 0%) in NSCLC patients taking PD-1/PD-L1inhibitors. Subgroup analyses indicated that the association between concomitant use of GAS and poor survival in NSCLC patients taking PD-L1inhibitors was consistent in univariate and multivariate studies (P values for subgroup difference both > 0.05 for PFS and OS).

CONCLUSIONS

The meta-analysis by summarizing the up-to-date literatures showed that use of GAS, primarily PPIs, may be associated with poor survival outcomes in patients with NSCLC receiving PD-1/PD-L1inhibitors.

TorR/TorS Two-Component system resists extreme acid environment by regulating the key response factor RpoS in Escherichia coli

Response to acid stress is critical for Escherichia coli to successfully complete its life-cycle. Acid resistance is an indispensable mechanism that allows neutralophilic bacteria, such as E. coli, to survive in the gastrointestinal tract. Escherichia coli acid tolerance has been extensively studied over the past decades, and most studies have focused on mechanisms of gene regulation. Bacterial two-component signal transduction systems sense and respond to external environmental changes through regulating genes expression. However, there has been little research on the mechanism of the TorR/TorS system in acid resistance, and how TorR/TorS regulate the expression ofacid-resistantgenes is still unclear. We found that TorR/TorS deletion in E. coli cells led to a growth defect in extreme acid conditions,andthis defectmightdepend on the nutritional conditionsand growth phase.TorS/TorR sensed an extremely acidic environment, and this TorR phosphorylation process might not be entirely dependent on TorS.RNA-seqand RT-qPCR results suggested that TorR regulated expressions of gadB, gadC, hdeA, gadE, mdtE, mdtF, gadX, and slp acid-resistant genes. Compared with wild-type cells, the stress response factor RpoSlevels and itsexpressions were significantly decreased in Δ torR cellsstimulated by extreme acid. And under these circumstances, the expression of iraM was significantly reduced to 0.6-fold inΔ torR cells. Electrophoreticmobility shift assay showed that TorR-His₆ could interact with the rpoS promoter sequence in vitro. β-galactosidase activity assayresultsapprovedthat TorR might bind the rpoS promoter region in vivo. After the mutation of the TorR-box in the rpoS promoter region, these interactions were no longer observed. Taken together, we propose thatTorS and potential Hanks model Ser/Thr kinase received an external acid stress signal and then phosphorylated TorR, which guided the expressions of a variety of acid resistance genes. Moreover,TorRcoped with extreme acid environmentsthroughRpoS, levels of which might be maintained byIraM. Finally,TorR may confer E. coli with the abilityto resist gastric acid, allowing the bacterium to reach the surface of the terminal ileum and large intestine mucosal epithelial cells through the gastric acid barrier, andestablishcolonization and pathogenicity.

Calcium Absorption from Food Products: Food Matrix Effects

This article reviews physicochemical aspects of calcium absorption from foods. Notable differences are observed between different food products in relation to calcium absorption, which range from <10% to >50% of calcium in the foods. These differences can be related to the interactions of calcium with other food components in the food matrix, which are affected by various factors, including fermentation, and how these are affected by the conditions encountered in the gastrointestinal tract. Calcium absorption in the intestine requires calcium to be in an ionized form. The low pH in the stomach is critical for solubilization and ionization of calcium salts present in foods, although calcium oxalate complexes remain insoluble and thus poorly absorbable. In addition, the rate of gastric transit can strongly affect fractional absorption of calcium and a phased release of calcium into the intestine, resulting in higher absorption levels. Dairy products are the main natural sources of dietary calcium in many diets worldwide, which is attributable to their ability to provide high levels of absorbable calcium in a single serving. For calcium from other food products, lower levels of absorbable calcium can limit contributions to bodily calcium requirements.

Astringent Gallic Acid in Red Wine Regulates Mechanisms of Gastric Acid Secretion via Activation of Bitter Taste Sensing Receptor TAS2R4

Red wine is rich in phenolic compounds, which chiefly determine its characteristic taste. One of its major phenolic acid constituents for which an astringency, yet no clear contribution to bitter taste has been reported, is gallic acid (GA). In previous studies, we have demonstrated bitter-tasting constituents to regulate cellular proton secretion (PS) as a key mechanism of gastric acid secretion via activation of bitter taste sensing receptors (TAS2Rs). Here, we hypothesized a contributing role of GA to the red wine-stimulated effect on PS in human gastric tumor cells (HGT-1 cells). Sensory analyses revealed that 10 μM GA as the lowest concentration tested more bitter than tap water, with increasing bitter ratings up to 1000 μM. In HGT-1 cells, the concentration of 10 μM GA evoked the most pronounced effect on PS secretion, either when added to cells as in-water solution or when spiked to a red wine matrix. GA-spiking of Zweigelt and Blaufränkisch red wine samples up to a concentration of 10 μM resulted in an equally stimulated PS, whereas the non-GA-spiked wine samples demonstrated contrary effects on PS, indicating a functional role of GA on PS. Involvement of TAS2R4 in the GA-induced PS was verified by means of an HGT-1 homozygote CRISPR-Cas9 TAS2R4 knockout approach. Moreover, gene expression analyses revealed GA to increase TAS2R4. These results demonstrate a functional role of TAS2R4 in GA-evoked PS as a key mechanism of gastric acid secretion aiding digestion. Moreover, our data provide mechanistic insights, which will help to produce stomach-friendly red wines.

Sham Feeding Induced Gastric Acid Secretion in Patients with Caustic Induced Esophageal Stricture

Caustic ingestion can lead to structural changes in the upper gastro-intestinal tract. However, there is limited data on the effect of caustic ingestion on gastric secretion. This study was planned to determine changes in gastric acid output after sham feeding in patients with caustic induced esophageal stricture and to compare it with healthy controls. It was a prospective study done at tertiary care center in North India. Consecutive patients with caustic induced esophageal stricture were evaluated for the study. Gastric secretory function was estimated in the basal state and after modified sham feeding. These results were compared with age-matched controls. The mean age of the included patients (n = 18) was 30.11 ± 9.19 years and 13 patients were male. 16 (88%) patients had history of acid ingestion. Patients with caustic sequelae had significantly lower basal and stimulated acid secretion compared to controls (n = 10) (5.84 ± 2.44 mmol/hr; p < 0.01 and 17.16 ± 7.53 mmol/hr; p < 0.01; respectively). Patients with lower esophageal stricture (n = 8) had significantly lower increase in acid output compared to patients with stricture elsewhere in esophagus (0.20 ± 0.3 vs. 2.31 ± 1.74 mmol/hr, p < 0.01). Patients with lower esophageal involvement had significantly lower stimulated acid secretion and increase in acid secretion compared to controls (4.74 ± 4.67 vs. 17.16 ± 7.53 mmol/hr; p < 0.01 and 20 ± 0.3 vs. 2.09 ± 0.88 mmol/hr; p < 0.01; respectively).

Gastric Acid Powered Nanomotors Release Antibiotics for In Vivo Treatment of Helicobacter pylori Infection

Helicobacter pylori (H. pylori) infection has ≈75% probability of causing gastric cancer, so it is considered to be the strongest single risk factor for gastric malignancies. However, the harsh gastric acid environment has created obstacles to medical treatment. This work reports a nanomotor with a bottle-shaped container that can be loaded with small molecules of clarithromycin, nano calcium peroxide (CaO₂ ), and Pt nanoparticles (Pt NPs) by ultrasound. Nanomotors can quickly consume gastric acid through the chemical reaction of CaO₂ to temporarily neutralize gastric acid. The product hydrogen peroxide (H₂ O₂ ) is catalytically decomposed into a large amount of oxygen (O₂ ) by Pt NPs. The local concentration gradient of O₂ bubbles causes it to be expelled from the nanobottles through a narrow opening, and then push the nanobottles forward to provide maximum release and prodrug efficacy. Experiments in animal models show that 15 mg nanomotors can safely and quickly neutralize gastric acid in the stomach and simultaneously release prodrugs to achieve good therapeutic effects without causing acute toxicity. H. pylori burden in mice was 2.6 orders of magnitude lower than that in the control group. The stomach returns to normal pH within 1 d after administration.

Association of Gastric Acid Suppression and Sorafenib Efficacy in Advanced Hepatocellular Carcinoma

BACKGROUND

Recent studies have revealed that coadministration of gastric acid suppressants reduces the efficacy of the tyrosine kinase inhibitors erlotinib and sunitinib in patients with non-small cell lung cancer and renal cell carcinoma, respectively. The authors have therefore assessed if the concurrent use of gastric acid suppressants and sorafenib impairs outcomes in patients with advanced hepatocellular carcinoma (HCC).

METHODS

A retrospective analysis was conducted on all patients treated with sorafenib for advanced HCC at a single tertiary referral unit in the United Kingdom, between January 2008 and January 2014. A multivariate Cox proportional hazard model was used to assess the effect of the concomitant use of gastric acid suppression and sorafenib on progression-free survival (PFS) and overall survival (OS).

RESULTS

Data were collected from 197 patients, of which 182 could be assessed for this study; 77 (42%) were on concurrent gastric acid suppression therapy. After adjusting for imbalances between the groups, a Cox regression analysis gave an adjusted hazard ratio for the concurrent acid suppression group compared with the no acid suppression group of 5.4 (95% confidence interval, 3.6-7.9) for PFS and 1.85 (95% confidence interval, 1.3-2.6) for OS.

CONCLUSIONS

This single-center experience shows that patients with advanced HCC taking sorafenib and concomitant gastric acid suppression therapy have significantly inferior PFS and OS. This is the first time that this negative interaction has been reported and further prospective validation is warranted.

[A pseudoallergic reaction involved in developing bullous oral lichen planus in patients with increased gastric acid-producing function]

Lichen planus of the oral mucosa (LPOOR) is a chronic autoimmune disease. With a complicated course of the disease, other clinical and pathomorphological signs are added to the clinical picture of the reticular form, including blisters in the bullous form of the disease. It is known that LPOOR develops mainly by the mechanism of delayed-type hypersensitivity reaction, and in complicated forms - with the addition of a true allergic reaction of immediate-type hypersensitivity.

OBJECTIVE

To determine the role of pseudo-allergic reaction in the development of the bullous form of LPR in patients with increased acid-forming function of the stomach.

MATERIAL AND METHODS

The level of histamine in blood was studied by high-performance liquid chromatography and blood IgE by the immunochemiluminescent method in 38 patients with the bullous form of LPOOR against the background of acid-dependent diseases and 14 patients with the reticular form of LP RR with the absence of hyperchlorhydria. For the treatment of patients with the bullous form of LPOOR, drugs were used - H1 and H2 receptor blockers and proton pump inhibitors.

RESULTS

A positive result was obtained in 68.4% of cases.

CONCLUSION

Thus, a pseudoallergic component has been established in the development of the bullous form of the LP of ROS against the background of increased acid-forming function of the stomach.

PECULIARITIES OF DETERMINING THE GASTRIC ACID SECRETION AND DIABETIC AUTONOMIC NEUROPATHY IN PATIENTS WITH CHRONIC PANCREATITIS AND TYPE 2 DIABETES

OBJECTIVE

The aim: Is to determine the peculiarities of changes in the gastric acid secretion against the background of diabetic autonomic neuropathy and autonomic dysfunction in patients with chronic pancreatitis (CP) and type 2 diabetes (T2DM).

PATIENTS AND METHODS

Materials and methods: We investigated 64 patients with CP and T2DM, who were included in the first group of the patients examined; Group II consisted of 40 patients with T2DM; and Group III of the patients examined consisted of 34 patients with CP.

RESULTS

Results: Differences were found in assessing the degree of autonomic nervous system (ANS) dysfunction in the examined patients, namely - the most pronounced ANS dysfunction according to the Wayne questionnaire was diagnosed in patients Group I, while patients of Group III. Analysis of gastric acid secretion indicates that no patients of Group III had normal acidity. Normal acidity is more often found in the second group of subjects. Both in patients with CP and T2DM, and in isolation with CP, moderate hyperacidity was more often determined.

CONCLUSION

Conclusions: The predominance of the parasympathetic division of the ANS, as well as manifestations of severe ANS dysfunction, are observed in patients with CP and T2DM. The prevalence of gastric hyperacidity on the background of DAN was established in patients with CP and T2DM. In this case, the absence of clinical symptoms or their minimal severity is determined, which indicates the lesion of the digestive tract in these patients.

Helicobacter pylori diversification during chronic infection within a single host generates sub-populations with distinct phenotypes

Helicobacter pylori chronically infects the stomach of approximately half of the world's population. Manifestation of clinical diseases associated with H. pylori infection, including cancer, is driven by strain properties and host responses; and as chronic infection persists, both are subject to change. Previous studies have documented frequent and extensive within-host bacterial genetic variation. To define how within-host diversity contributes to phenotypes related to H. pylori pathogenesis, this project leverages a collection of 39 clinical isolates acquired prospectively from a single subject at two time points and from multiple gastric sites. During the six years separating collection of these isolates, this individual, initially harboring a duodenal ulcer, progressed to gastric atrophy and concomitant loss of acid secretion. Whole genome sequence analysis identified 1,767 unique single nucleotide polymorphisms (SNPs) across isolates and a nucleotide substitution rate of 1.3x10-4 substitutions/site/year. Gene ontology analysis identified cell envelope genes among the genes with excess accumulation of nonsynonymous SNPs (nSNPs). A maximum likelihood tree based on genetic similarity clusters isolates from each time point separately. Within time points, there is segregation of subgroups with phenotypic differences in bacterial morphology, ability to induce inflammatory cytokines, and mouse colonization. Higher inflammatory cytokine induction in recent isolates maps to shared polymorphisms in the Cag PAI protein, CagY, while rod morphology in a subgroup of recent isolates mapped to eight mutations in three distinct helical cell shape determining (csd) genes. The presence of subgroups with unique genetic and phenotypic properties suggest complex selective forces and multiple niches within the stomach during chronic infection.

Gastric acid level of humans must decrease in the future

Proton pump inhibitors strongly inhibit gastric acid production, but digestion problems do not generally arise. We can intake almost ordinary food even after total gastrectomy. Small intestine itself can digest and absorb food using various digestive enzymes without digestion in the stomach. The pH level of gastric acid in humans is much lower than that of most animals, and very close to that of carrion-eating animals called scavengers. It is assumed that ancient humans became bipedal approximately 4 million years ago. It was difficult for humans, who just started unstable bipedal locomotion, to catch quadrupedal-walking animals that can move faster, without special hunting tools. They may have eaten remaining carcasses, which is mainly the leftovers of carnivora species, as animal-derived food. The benefit to produce a volume of gastric acid for humans is carrion eating, in which disinfection by gastric acid is important. Humans produce a high concentration of gastric acid to enable consumption of a diet containing some bacteria and support this lifestyle by consuming significant energy to protect themselves from gastric acid. Now, the opportunity for strong deleterious bacteria to enter the gastrointestinal tract has decreased because of the organized clean environment. If this hygienic environment is maintained for a long time, our gastric acid level must be decreased gradually.

Upper Gastrointestinal Disease Influences the Occurrence of Inflammatory Bowel Disease

BACKGROUND AND AIMS

Compromise of the gastric acid barrier may facilitate bacterial invasion of the lower intestinal tract and influence the occurrence of inflammatory bowel disease (IBD). Our study tested the associations between histopathologic changes in the upper and lower gastrointestinal tract in patients undergoing bidirectional endoscopy.

METHODS

The Inform Diagnostics database is a national electronic repository of histopathologic records of patients distributed throughout the entire USA. A case-control study among 302,061 patients, of whom 13,943 harbored IBD, evaluated whether the occurrence of Crohn's disease or ulcerative colitis was influenced by the presence of various upper gastrointestinal diagnoses associated with lowered gastric acid output. The influence of individual risk factors on the occurrence of colonic disease was expressed as odds ratios with their 95% confidence intervals.

RESULTS

The odds ratio for Crohn's disease being associated with gastric H. pylori was 0.30 (0.24-0.37), with intestinal metaplasia 0.30 (0.24-0.39), with fundic gland polyps 0.42 (0.35-0.50), with gastric hyperplastic polyps 0.35 (0.23-0.51), with Barrett's metaplasia 0.19 (0.14-0.24), and with reflux esophagitis 0.46 (0.42-0.51). The odds ratio for ulcerative colitis being associated with gastric H. pylori was 0.58 (0.50-0.67), with intestinal metaplasia 0.39 (0.32-0.47), with fundic gland polyps 0.61 (0.53-0.71), with gastric hyperplastic polyps 0.64 (0.49-0.84), with Barrett's metaplasia 0.50 (0.43-0.59), and with reflux esophagitis 0.77 (0.71-0.84).

CONCLUSIONS

A diminished gastric acid barrier function, as evidenced by various upper gastrointestinal diseases associated with lowered gastric acid output, may exert a protective influence against the development of inflammatory bowel disease.

Effects of Clarithromycin Administration on Gastric Acid Secretion and Cytoprotection in Wistar Rats

The incidence of peptic ulcer disease in Nigeria is 28% (Ndububa and Adeyemi, 2008). Clarithromycin (CLX) is used in the treatment of peptic ulcer owing to its antibacterial effect. Whether CLX has effects on other gastrointestinal parameters that reduce peptic ulcer has not been previously investigated. Therefore the effects of CLX on gastric acid secretion, mucus secretion and gastric ulcer scores in rats were investigated. A total of 30 albino wistar rats were used for the study. Out of this number, 10 rats each were used for gastric acid secretion, mucus secretion and ulcer scores respectively. In each of these sub groups, 5 rats served as test and were treated with CLX orally and 5 rats served as control. Standard methods were used for the estimation of these parameters of gastric function. The results showed that basal gastric acid, peak acid output following histamine stimulation and mucus secretion were significantly increased (p<0.001) in CLX-treated (test) rats than in their control. Furthermore, ulcer scores were significantly reduced (p<0.001) in the CLX-treated rats than control. In conclusion, Clarithromycin administration reduced gastric ulcers in rats. This may be attributable to not only its antibiotic property but also its ability to increase gastric mucus which counteracts the aggressive effect of the acid.

[A Survey on the Concurrent Administration of Erlotinib and Gastric Acid Suppressing Medications among Doctors:Concern for Drug Interaction]

Erlotinibis known as a key drug for the treatment of non-small-cell lung cancer. It is known to interact with gastric acid suppressing medications(AS). Concurrent administration of erlotinibwith AS is reported to decrease AUC and Cmax of erlotinib. From the result of a survey on concurrent administration of erlotinib with AS in our hospital, we considered that intake of erlotinib between meals in the morning and intake of AS after dinner or at bedtime certainly reduce the chance of drug interactions to a minimum. We suggested a direction of use of erlotinibto the doctors who used to prescribe this medication in their daily medical practice. We surveyed the doctors' perceptions of drug interactions. The results of the survey showed that 29% of the doctors were not concerned about drug interactions, although 81% of the doctors approved our proposal. By providing a suggestion for drug administration by analyzing drug information, the expectations of the doctors can be met and it also demonstrates the efficiency of pharmacists.

Veverimer versus placebo in patients with metabolic acidosis associated with chronic kidney disease: a multicentre, randomised, double-blind, controlled, phase 3 trial

BACKGROUND

Patients with advanced chronic kidney disease lose the capacity to fully excrete endogenous acid, resulting in chronic metabolic acidosis that increases the risk of disease progression and causes muscle catabolism and bone resorption. Veverimer, a non-absorbed, counterion-free, polymeric drug, selectively binds and removes hydrochloric acid from the gastrointestinal lumen, unlike current oral sodium bicarbonate therapy for metabolic acidosis that only neutralises accumulated acid. We assessed the efficacy and safety of veverimer as a treatment for metabolic acidosis in patients with chronic kidney disease.

METHODS

We did a multicentre, parallel, randomised, double-blind, placebo-controlled study at 37 sites (hospitals and specialty clinics) in Bulgaria, Croatia, Georgia, Hungary, Serbia, Slovenia, Ukraine, and the USA. Eligible participants were patients aged 18-85 years with non-dialysis-dependent chronic kidney disease (estimated glomerular filtration rate of 20-40 mL/min per 1·73 m²) and metabolic acidosis (serum bicarbonate concentration of 12-20 mmol/L). Patients were randomly assigned (4:3) to veverimer 6 g/day or placebo for 12 weeks while they consumed their typical diet. Both drugs were taken as oral suspensions in water with lunch. Randomisation was done by study site personnel with a computer-generated randomisation code with balanced permuted blocks (block size of seven) and stratified by baseline bicarbonate (≤18 mmol/L vs >18 mmol/L). Patients and investigators were masked to treatment allocation; however, because the appearance of placebo differed from veverimer, a non-masked site staff member who had no other role in the study dispensed, prepared, and supervised dosing of the study drugs. The composite primary efficacy endpoint was the difference (veverimer-placebo) in the proportion of patients achieving at week 12 either an increase of 4 mmol/L or more from baseline in serum bicarbonate concentration or serum bicarbonate in the normal range of 22-29 mmol/L, assessed in the modified intention-to-treat population (all patients with a baseline and at least one post-baseline serum bicarbonate value). Patients fasted for at least 4 h (consuming only water) before measurements of bicarbonate. Safety was assessed in all patients who received any amount of study drug. This trial is registered with ClinicalTrials.gov, number NCT03317444.

FINDINGS

Between Sept 26, 2017, and Feb 9, 2018, we randomly assigned 124 participants to veverimer and 93 to placebo. The composite primary endpoint was met by 71 (59%) of 120 patients in the veverimer group versus 20 (22%) of 89 patients in the placebo group (a difference of 37%, 95% CI 23-49; p<0·0001). The most common body system in which adverse events in the veverimer group occurred was gastrointestinal; of these, non-treatment limiting diarrhoea was the most common event (11 [9%] vs three [3%] in the veverimer and placebo groups, respectively). The most common treatment-related adverse events were gastrointestinal (diarrhoea, flatulence, nausea, and constipation) occurring in 16 (13%) patients with veverimer and five (5%) patients with placebo. Two deaths occurred during the study, both in the placebo group (unstable angina and pneumonia).

INTERPRETATION

Veverimer effectively and safely corrected metabolic acidosis. Longer-term studies are warranted to assess the effects of veverimer on physical functioning and to assess other deleterious consequences of metabolic acidosis including progression of chronic kidney disease and bone health.

FUNDING

Tricida.

Pea Ferritin Stability under Gastric pH Conditions Determines the Mechanism of Iron Uptake in Caco-2 Cells

Background

Iron deficiency is an enduring global health problem that requires new remedial approaches. Iron absorption from soybean-derived ferritin, an ∼550-kDa iron storage protein, is comparable to bioavailable ferrous sulfate (FeSO4). However, the absorption of ferritin is reported to involve an endocytic mechanism, independent of divalent metal ion transporter 1 (DMT-1), the transporter for nonheme iron.

Objective

Our overall aim was to examine the potential of purified ferritin from peas (Pisum sativum) as a food supplement by measuring its stability under gastric pH treatment and the mechanisms of iron uptake into Caco-2 cells.

Methods

Caco-2 cells were treated with native or gastric pH-treated pea ferritin in combination with dietary modulators of nonheme iron uptake, small interfering RNA targeting DMT-1, or chemical inhibitors of endocytosis. Cellular ferritin formation, a surrogate measure of iron uptake, and internalization of pea ferritin with the use of specific antibodies were measured. The production of reactive oxygen species (ROS) in response to equimolar concentrations of native pea ferritin and FeSO4 was also compared.

Results

Pea ferritin exposed to gastric pH treatment was degraded, and the released iron was transported into Caco-2 cells by DMT-1. Inhibitors of DMT-1 and nonheme iron absorption reduced iron uptake by 26-40%. Conversely, in the absence of gastric pH treatment, the iron uptake of native pea ferritin was unaffected by inhibitors of nonheme iron absorption, and the protein was observed to be internalized in Caco-2 cells. Chlorpromazine (clathrin-mediated endocytosis inhibitor) reduced the native pea ferritin content within cells by ∼30%, which confirmed that the native pea ferritin was transported into cells via a clathrin-mediated endocytic pathway. In addition, 60% less ROS production resulted from native pea ferritin in comparison to FeSO4.

Conclusion

With consideration that nonheme dietary inhibitors display no effect on iron uptake and the low oxidative potential relative to FeSO4, intact pea ferritin appears to be a promising iron supplement.

Characterization of the seven-day course of pulmonary response following unilateral lung acid injury in rats

BACKGROUND

Aspiration of gastric acid is an important cause of acute lung injury. The time course of the pulmonary response to such an insult beyond the initial 48 hours is incompletely characterized. The purpose of this study was to comprehensively describe the pulmonary effects of focal lung acid injury over a seven day period in both directly injured and not directly injured lung tissue.

METHODS

Male Wistar rats underwent left-endobronchial instillation with hydrochloric acid and were sacrificed at 4, 24, 48, 96 or 168 h after the insult. Healthy non-injured animals served as controls. We assessed inflammatory cell counts and cytokine levels in right and left lung lavage fluid and blood, arterial oxygen tension, alterations in lung histology, lung wet-to-dry weight ratio and differential lung perfusion.

RESULTS

Lung acid instillation induced an early strong inflammatory response in the directly affected lung, peaking at 4-24 hours, with only partial resolution after 7 days. A less severe response with complete resolution after 4 days was seen in the opposite lung. Alveolar cytokine levels, with exception of IL-6, only partially reflected the localization of lung injury and the time course of the functional and histologic alterations. Alveolar leucocyte subpopulations exhibited different time courses in the acid injured lung with persistent elevation of alveolar lymphocytes and macrophages. After acid instillation there was an early transient decrease in arterial oxygen tension and lung perfusion was preferentially distributed to the non-injured lung.

CONCLUSION

These findings provide a basis for further research in the field of lung acid injury and for studies exploring effects of mechanical ventilation on injured lungs. Incomplete recovery in the directly injured lung 7 days after acid instillation suggests that increased vulnerability and susceptibility to further noxious stimuli are still present at that time.

Geochemical investigation of potentially harmful elements in household dust from a mercury-contaminated site, the town of Idrija (Slovenia)

A comprehensive geochemical investigation of potentially harmful elements (PHEs) in household dust from the town of Idrija (Slovenia), once a world-famous Hg mining town that is now seriously polluted, was performed for the first time. After aqua regia digestion, the content of mercury (Hg), arsenic (As), cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), molybdenum (Mo), nickel (Ni), lead (Pb) and zinc (Zn) was measured. PHE-bearing particles were recognised and observed by scanning electron microscopy and energy-dispersive spectrometry before and after exposure to simulated stomach acid (SSA). Mercury binding forms were identified by Hg thermal desorption technique and gastric bioaccessible Hg was estimated after SSA extraction by ICP-MS. With regard to rural and urban background values for Slovenia, high Hg content (6-120 mg/kg) and slightly elevated As content (1-13 mg/kg) were found. Mercury pollution is a result of past mining and ore processing activities. Arsenic content is potentially associated with As enrichment in local soils. Four Hg binding forms were identified: all samples contained Hg bound to the dust matrix, 14 samples contained cinnabar, two samples contained metallic Hg (Hg⁰), and one sample assumingly contained mercury oxide. After exposure to SSA, Hg-bearing phases showed no signs of dissolution, while other PHE-bearing phases were significantly morphologically and/or chemically altered. Estimated gastric Hg bioaccessibility was low (<0.006-0.09 %), which is in accordance with identified Hg binding forms and high organic carbon content (15.9-31.5 %) in the dust samples.

Helicobacter pylori, HIV and Gastric Hypochlorhydria in the Malawian Population

BACKGROUND

HIV and Helicobacter pylori are common chronic infections in sub-Saharan Africa. Both conditions can predispose to gastric hypochlorhydria that may be a risk factor for enteric infections and reduced drug absorption. We have investigated to what extent HIV and H. pylori infections are associated with hypochlorhydria in a Malawian cohort of patients undergoing endoscopy.

METHODS

104 sequential symptomatic adults referred for gastroscopy at Queen Elizabeth Central Hospital, Blantyre, Malawi, had blood taken for rapid HIV testing and fasting serum gastrin analysis. Gastric fluid was aspirated for pH testing, and gastric biopsies were taken.

RESULTS

After 9/104 HIV-infected patients who were already established on anti-retroviral therapy were excluded, 17/95 (25.0%) were seropositive for untreated HIV, and 68/95 (71.6%) patients were H. pylori positive by histology. Hypochlorhydria (fasting gastric pH>4.0) was present in 55.8% (53/95) of patients. H. pylori infection was significantly associated with hypochlorhydria (OR 2.91, [1.02-7.75], p=0.046). While single infection with HIV was not significantly independently associated with hypochlorhydria. H. pylori and HIV co-infection was more strongly associated with hypochlorhydria (OR 6.25, [1.33-29.43], p=0.020) than either infection alone, suggesting an additive effect of co-infection. HIV infection was associated with higher serum gastrin levels (91.3 pM vs. 53.1 pM, p=0.040), while H. pylori infection was not (63.1 pM vs. 55.1 pM, p=0.610). Irrespective of H. pylori and HIV status, most patients (>90%) exhibited pangastritis. Only three patients had histological evidence of gastric atrophy, of which only one was HIV-infected.

CONCLUSION

H. pylori infection was associated with fasting hypochlorhydria, while HIV was not independently associated. HIV and H. pylori co-infection, however, was more strongly associated with hypochlorhydria than H. pylori infection alone. The mechanism of this apparent additive effect between HIV and H. pylori remains unclear, but appears to be related to chronic pangastritis rather than gastric atrophy, and associated with hypergastrinaemia in HIV-infected individuals.

[Role of acid in functional dyspepsia]

Recently, the Japanese Society of Gastroenterology (JSGE) developed an evidence-based clinical guideline for functional dyspepsia (FD). Multiple factors (including disturbance of gastric motility and hypersensitivity) may be associated with the pathophysiology of FD. Among these, acid plays a crucial role in the pathogenesis of FD. The presence of gastric acid affects gastric motility and sensitivity. Additionally, duodenal acidification induces proximal gastric relaxation and hypersensitivity to gastric distension. Systematic review showed that proton pump inhibitors (PPIs) and histamine type -2 receptor antagonists (H2RAs) are effective for the treatment of FD as the first line therapy, and both provide same level efficacy.

Risk of spontaneous bacterial peritonitis associated with gastric Acid suppression

The primary objective of this study was to determine the association between the use of gastric acid suppressants (GAS) and the risk of developing spontaneous bacterial peritonitis (SBP) in patients with advanced liver cirrhosis (LC). A case-control study nested within a cohort of 480,000 representatives of Taiwan National Health Insurance beneficiaries was carried out. A case was matched with 100 controls on age, gender, and index date of SBP diagnosis. GAS use was identified from the 1-year period before the index date. Conditional logistic regression analysis was used to adjust for various unbalanced covariates between users and nonusers of GAS. A total of 947 cases of SBP were identified among the 86,418 patients with advanced LC. A significant increased risk of developing SBP was found to be associated with current (within 30 days), and recent (within 30-90 day) use of 2 different classes of GAS: proton pump inhibitors (PPIs) and histamine 2 receptor antagonists (H2RAs). The confounder adjusted rate ratio (aRR) for the current use of PPIs was 2.77 (95% CI: 1.90-4.04) and H2RAs was 2.62 (95% CI: 2.00-3.42). The risk of SBP attenuated for the recent use of PPIs (aRR: 2.20, 95%CI: 1.60-3.02) or H2RAs (aRR: 1.72, 95% CI: 1.25-2.37). In addition, sensitivity analysis using hospitalized SBP as the primary outcome showed a similar risk for the current use of PPIs (aRR, 3.24; 95% CI: 2.08-5.05) and H2RAs (aRR 2.43; 95% CI 1.71-3.46). Furthermore, higher cumulative days of gastric acid suppression were associated with a higher risk of SBP (trend P < 0.0001). To conclude, exposure to GAS was associated with an increased risk of SBP in patients with advanced LC. The association was more pronounced in current PPI users compared with nonusers.

Bile acids but not acidic acids induce Barrett's esophagus

Barrett's esophagus (BE) is associated with the development of esophageal adenocarcinoma (EAC). Bile acids (BAs) refluxing into the esophagus contribute to esophageal injury, which results in BE and subsequent EAC. We developed two animal models to test the role of BAs in the pathogenesis of BE. We surgically generated BA reflux, with or without gastric acid, in rats. In a second experiment, we fed animals separately with BAs and gastric acid. Pathologic changes were examined and the expression of Muc2 and Cdx2 in BE tissue was tested by immunostaining. Inflammatory factors in the plasma, as well as differentiation genes in BE were examined through highly sensitive ELISA and semi-quantitative RT-PCR techniques. We found that BAs are sufficient for the induction of esophagitis and Barrett's-like metaplasia in the esophagus. Overexpression of inflammatory cells, IL-6, and TNF-α was observed both in animals fed with BAs and surgically generated BA reflux. Furthermore, elevated levels of Cdx2, Muc2, Bmp4, Kit19, and Tff2 (differentiation genes in BE) were found in BA-treated rats. In conclusion, BAs, but not gastric acid, are a major causative factor for BE. We confirmed that BAs contribute to the development of BE by inducing the inflammatory response in the esophagus. Inhibiting BAs may be a promising therapy for BE.